Dual control mechanism

ABSTRACT

An electrical control device is disclosed, in which a push-pull rotatable shaft can be moved longitudinally between two positions, in each of which it engages a different potentiometer control sleeve, so that two potentiometers can be alternatively adjusted by a single shaft. Biasing means are provided to discourage inadvertent adjustment of one of the potentiometers.

United States Patent Ontario, Canada Urwin 51 Oct. 10, 1972 [541 DUAL CONTROL MECHANISM 2,650,270 8/1953 Mucher ..33s/129 x 2,716,874 9/1955 Wiley ..338/l98 x [72] Invent 1 waterlm' 2,941,175 6/1960 Zarrillo .;.....33s/134 2,942,221 6/1960 Girolamo ..338/200 [73] Assignee: Electrohome Limited, Kitchener, 3,611,245 10/1971 Puerner ..338/ 134 Primary Examiner--Lewis H. Myers [22] Flled 1971 Assistant Examiner-U. Weldon [21] Appl. No.: 191,407 Attorney-Peter W. McBurney et a1.

4 57 ABSTRACT [52] US. Cl. 338/131, 338/172, 338/198 1 511 1111.01... .QHOlc 5/04 An electrical control devlce 1S dlsclosed, whlch [58] Field of Search ..33s/12s-134 166 ramble shaft can be longitudinally 338/172 198 between two positions, in each of which it engages a different potentiometer control sleeve, so that two potentiometers can be alternatively adjusted by a sin- [56] References Cited gle shaft. Biasing means are provided to discourage in- UNITED STATES PATENTS advertent adjustment of one of the potentiometers. 2,469,924 5/1949 I Kunz ......338/ 130 X 6 Clains, 2 Drawing Figures 32 32 JO 12 24 22 22 34 24 g 49 4s 53 N i 5 37 36 14 2O 16 7 5 54 1 1 j 56 -18 I l/l/ [I ;f'.::;: i;:- -i L" -2 v; y i 2 I k I l9 18 58, f z i I I 1"-\ 1 I 7:217 3'1 2'8 30 2e DUAL CONTROL MECHANISM This invention relates generally to electrical control devices, and has to do particularly with the design of a two-potentiometer control, especially adapted for use in color television, although not necessarily restricted thereto.

In the radio and television industry, it is often desirable to enable the user of receiving apparatus to make two adjustments with a single control knob. The adjustments here spoken of are the continuous range type, such as volume control, tinting in color television, brightness of television image, etc. Generally speaking, all such continuous range adjustments require a potentiometer, and the most common type of potentiometer is of the circular or rotary type, in which the adjustment is made by rotating the control knob and thus the control shaft. Often, the rotor of the potentiometer rotates with the shaft, while the slider (which picks up the divided voltage) is stationary.

One particular application of the two-potentiometer adjustment device of this invention will now be described with respect to color television, but this application is not to be considered in any way limiting.

In color television, it is important to enable the user to control the tint on the screen, i.e., the blending of the component colors which go to make up the picture. Turned too far in one direction, the picture becomes purple, while in the other direction the picture goes into the red area. One of the most important considerations for pleasant viewing is that the flesh tints be as true-to-life as possible. In the transmission of the color signal, each band of color is represented by a certain phase shift with respect to a particular base frequency, and the flesh tone, generally speaking, is represented by a phase shift falling within a certain rather narrow range. Many color television sets have a built-in circuit which the user can actuate and which enables the television receiver to recognize a flesh tone phase shift provided it falls within a given predetermined range, and which further enables the'television receiver to tune itself automatically to that location in the tint range which will make the flesh tone true-to-life.

It occasionally happens, however, that a television signal received by the set is such that the phase shift intended to represent the flesh tone lies outside of the range within which the automatic recognition circuit mentioned above can operate. Thus, even though the user activates the recognition circuit, hands and faces do not appear at their proper flesh tone. It is then desirable to enable the user to alter the range within which the recognition circuit can operate, and this requires, among other things, a separate potentiometer.

The device of the present invention would enable a user to adjust either the general tint of a picture or the flesh tone recognition range of the automatic circuit with a single control knob.

It is the object of this invention to provide a control device by which the selective, non-simultaneous adjustment of two potentiometers can be accomplished through the manipulation of a single control shaft.

Accordingly, this invention provides an electrical control device, comprising housing means, first sleeve means mounted for rotation about an axis fixed with respect to the housing means and restrained against axial movement, a first potentiometer within the housing means and having first control means whereby rotation of the first sleeve means with respect to the housing means adjusts the first potentiometer, second sleeve means mounted for rotation about said axis independently of said first sleeve means and restrained against axial movement, a second potentiometer within said housing means and having second control means whereby rotation of the second sleeve means with respect to the housing means adjusts the second potentiometer, a control shaft through both the first and second sleeve means, the control shaft being axially slidable and independently rotatable with respect to said first and second sleeve means, first engagement means adapted to lock said control shaft to said first sleeve means when said control shaft moves into a first axial location, such that rotation of the control shaft in said first axial location adjusts the first potentiometer, and second engagement means adapted to lock said control shaft to said second sleeve means when said control shaft moves into a second axial location, such that rotation of the control shaft in said second axial location adjusts the second potentiometer.

One embodiment of this invention is shown in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:

FIG. 1 is an axial sectional view of the control device of this invention; and

FIG. 2 is a perspective view of the control device shown in FIG. 1.

In the FIGS. a control device generally indicated by the numeral 10 is seen to include a housing 12, a first sleeve member 14, a second sleeve member 16, a control shaft 18, a first pin 19 and a second pin 20. The housing 12 includes two generally disc-like non-conductive members 22 having secured thereto two cup members 24. Each non-conductive member 22, with its cup member 24, defines a radially symmetrical enclosure generally concentric with the control shaft 18. The first and second sleeve members 14 and 16 extend in opposite directions out of the housing 12, and it can be seen that the inner ends of the two sleeve members terminate respectively in the two enclosures defined between the non-conductive members 22 and the cup members 24. The first sleeve member 14 terminates in a first enclosure 26, while the second sleeve member 16 terminates in a second enclosure 28. Mounted on the inner end of the first sleeve member 14 within the enclosure 26 is a first potentiometer rotor 30, which is adapted torotate with the sleeve member 14. Mounted on the inner end of the second sleeve member 16 within the second enclosure 28 is a second potentiometer rotor 31, which is adapted to rotate with the second sleeve member 16. Secured to each non-conductive member 22 are three terminals 32. Of the three terminals 32 on each non-conductive member 22, one is electrically connected to a slider 34, while the other two are connected to either end of the potentiometer rotor. Secured to the rightward non-conductive member 22 is a mounting sleeve 36 which embraces the first sleeve member 14 without preventing rotation of the latter. The mounting sleeve 36 has threads 37 on its outer surface adapted to receive the usual mounting nut (not shown).

Secured to the leftward cup member 24 is a base plate 39 which carries a switch 40 having a switch actuator 42, which is adapted to slide longitudinally in the plane of the drawing, as shown by the two-headed arrow. Limit bars 44 are provided at either end of the range through which the switch actuator 42 can move. Terminals 46 on the bottom of the switch 40 are provided for making the usual contacts to the switch 40.

On the leftward end of the control shaft 18 are mounted a first disc 48 and a second disc 49. The first disc 48 is secured to the shaft 18 such that it cannot move axially with respect thereto. The second disc 49 has an integral sleeve 53 which fits snugly but slidably around the control shaft 18. The second disc 49 is capable of axial motion with respect to the control shaft 18. A compression coil spring 54, concentric with the control shaft 18 bears with its one end against the pin 20, and with its other end against the second disc 49, continuously urging the second disc 49 in the leftward direction, toward the first disc 48. The switch actuator 42 is captured between the first and second discs 48 and 49, as shown in FIG. 1, such that axial movement of the control shaft 18 causes the switch actuator 42 to move in a direction parallel with the shaft 18.

The first sleeve member 14 has, in its rightward end, two diametral V-slots 56 (only one visible in FIG. 1), while the second sleeve member 16 has, in its leftward end, two diametral V-slots 58 (only one visible in FIG. 1).

In order to adjust the setting of the leftward potentiometer (potentiometer rotor 31), the control shaft 18 is pulled outwardly to the right by the operator until the pin engages the diametral V-slots 58 in the second sleeve member 16. Shaft rotation will then adjust potentiometer rotor 31. By so doing, the operator also pulls the switch actuator 42 to its furthest rightward position as seen in FIG. 1 and this position is assumed to be the one in which the switch 40 brings the potentiometer rotor 31 into the required circuit.

The potentiometer rotor 31 is here assumed to be that controlling the general tint of a color television tube, while the potentiometer rotor 30 is assumed to be that which controls the range within which the automatic flesh-tone control can recognize the flesh-tone phase shift in the signal. Ordinarily, it would be undesirable to adjust the potentiometer rotor 30 inadvertently, since the flesh-tone recognition range is very carefully set at the factory. For this reason, even if the operator should shove the control shaft 18 inwardly or leftwardly in FIG. 1, mistakenly thinking that he would be able to adjust the potentiometer rotor 31, he would not push the control shaft 18 far enough for the pin 19 to engage the V-slots 56, because the switch actuator 42 would reach the leftward end of its range before engagement of the pin 19 with the V-slots 56, and this arrest of the switch actuator 42 would also arrest the second disc 49, which in turn would arrest the leftward end of the compression coil spring 54, such that the latter would strongly resist further leftward movement of the control shaft 18 by virtue of its pressure against the pin 20.

If the occasion should arise, however, where it is desirable to adjust the flesh tone recognition range of the automatic flesh tone control of the television set, then the operator would push the control shaft 18 leftwardly in FIG. 1, and would increase the pressure to overcome the resistance of the compression coil spring 54, thereby engaging'the pin 19 with the V-slots 56. Once this engagement has taken place, the operator can rotate the control shaft 18 to adjust the setting of the potentiometer rotor 30, which we are assuming controls the flesh tone recognition range. When the switch actuator 42 is in its leftward extreme position as seen in FIG. 1, the switch 40 throws the potentiometer rotor 30 into its required circuit.

It is to be appreciated that the switch 40, the switch actuator 42, and the first and second discs 48 and 49 are not essential to this invention. It may be possible or desirable, for example, to have the two potentiometer rotors 30 and 31 always alive and connected into their proper circuits, particularly for applications other than color television tint control.

It is further to be understood that there may well be applications of the device here disclosed in which it is unnecessary to provide an obstacle to the adjustment of one of the potentiometers. In such cases, the compression coil spring 45 can be dispensed with. Where it is desirable, however, that one of the potentiometer rotors be free of the risk of inadvertent adjustment, it will be necessary to provide the compression coil spring 54 and some element which is restrained against movement in the leftward direction in FIG. 1 beyond a certain point with respect to the housing 12. In the embodiment shown, the second disc 49 constitutes this member, since the second disc 49 cannot move further leftward than that position corresponding to the leftward limit of the switch actuator.

It should also be appreciated that the first and second sleeve members 14 and 16 may have more than two V- slots, or indeed may have any other conventional engagement means by which the control shaft can be moved axially into locking engagement with a sleeve member.

What I claim as my invention is:

1. An electrical control device, comprising: housing means,

first sleeve means mounted for rotation about an axis fixed with respect to said housing means and restrained against axial movement,

a first potentiometer within said housing means and having first control means whereby rotation of the first sleeve means with respect to the housing means adjusts the first potentiometer,

second sleeve means mounted for rotation about said axis independently of said first sleeve means and restrained against axial movement,

a second potentiometer within said housing means and having second control means whereby rotation of the second sleeve means with respect to the housing means adjusts the second potentiometer,

a control shaft through both the first and second sleeve means, the control shaft being axially slidable and independently rotatable with respect to said first and second sleeve means,

first engagement means adapted to lock said control shaft to said first sleeve means when said control shaft moves into a first axial location, such that rotation of the control shaft in said first axial location adjusts the first potentiometer,

and second engagement means adapted to lock said control shaft to said second sleeve means when said control shaft moves into a second axial location, such that rotation of the control shaft in said second axial location adjusts the second potentiometer.

2. The invention claimed in claim 1, further including resilient means tending to urge the control shaft away from said first axial location, such that the resilient means must be overcome in order for the control shaft to reach said first axial location.

3. The invention claimed in claim 1, in which each of said engagement means includes a projection on the control shaft and a recess on the respective sleeve means adapted to receive the projection upon axial sliding movement of the control shaft.

4. The invention claimed in claim 3, in which said projection is a removable pin lodged snugly in a diametral bore in said control shaft.

5. The invention claimed in claim 2, in which said second engagement means includes a pin lodged snugly in a diametral bore in the control shaft and a recess on said second sleeve means adapted to receive the pin upon axial sliding movement of the control shaft, and in which the resilient means is a compression coil spring bearing with one end against said pin and with the other end against a member restrained against movement away from the pin beyond a certain point with respect to the housing means.

6. The invention claimed in claim 1, in which said first and second sleeve means are constituted respectively by first and second aligned cylindrical sleeve members extending in opposite directions out of the housing means, the first and second sleeve members carrying upon their ends within the housing means the rotors of the first and second Potentiometers respectively, the outwardly extending end of each sleeve member having diametrally opposed V-notches in its periphery, two diametral pins lodged through the control shaft, one beyond each sleeve member, the portion of the control shaft lying beyond the second sleeve member and beyond the respective diametral pin carrying a first disc fixed axially with respect to the control shaft and a second disc between the first disc and the respective diametral pin, the second disc being axially slidable along the control shaft, a compression coil spring between the second disc and the last-mentioned pin urging the second disc toward the first disc, the invention further including a switch box fixed to said housing means and having a switch actuator adapted to slide parallel with the control shaft, the switch actuator projecting between said two discs and having a limit position in the direction away from the second cylindrical sleeve so located as to cause the spring to resist pressure tending to urge the pin adjacent the first cylindrical sleeve member into its respective V-notches. 

1. An electrical control device, comprising: housing means, first sleeve means mounted for rotation about an axis fixed with respect to said housing means and restrained against axial movement, a first potentiometer within said housing means and having first control means whereby rotation of the first sleeve means with respect to the housing means adjusts the first potentiometer, second sleeve means mounted for rotation about said axis independently of said first sleeve means and restrained against axial movement, a second potentiometer within said housing means and having second control means whereby rotation of the second sleeve means with respect to the housing means adjusts the second potentiometer, a control shaft through both the first and second sleeve means, the control shaft being axially slidable and independently rotatable with respect to said first and second sleeve means, first engagement means adapted to lock said control shaft to said first sleeve means when said control shaft moves into a first axial location, such that rotation of the control shaft in said first axial location adjusts the first potentiometer, and second engagement means adapted to lock said control shaft to said second sleeve means when said control shaft moves into a second axial location, such that rotation of the control shaft in said second axial location adjusts the second potentiometer.
 2. The invention claimed in claim 1, further including resilient means tending to urge the control shaft away from said first axial location, such that the resilient means must be overcome in order for the control shaft to reach said first axial location.
 3. The invention claimed in claim 1, in which each of said engagement means includes a projection on the control shaft and a recess on the respective sleeve means adapted to receive the projection upon axial sliding movement of the control shaft.
 4. The invention claimed in claim 3, in which said projection is a removable pin lodged snugly in a diametral bore in said control shaft.
 5. The invention claimed in claim 2, in which said second engagement means includes a pin lodged snugly in a diametral bore in the control shaft and a recess on said second sleeve means adapted to receive the pin upon axial sliding movement of the control shaft, and in which the resilient means is a compression coil spring bearing with one end against said pin and with the other end against a member restrained against movement away from the pin beyond a certain point with respect to the housing means.
 6. The invention claimed in claim 1, in which said first and second sleeve means are constituted respectively by first and second aligned cylindrical sleeve members extending in opposite directions out of the housing means, the first and second sleeve members carrying upon their ends within the housing means the rotors of the first and second potentiomEters respectively, the outwardly extending end of each sleeve member having diametrally opposed V-notches in its periphery, two diametral pins lodged through the control shaft, one beyond each sleeve member, the portion of the control shaft lying beyond the second sleeve member and beyond the respective diametral pin carrying a first disc fixed axially with respect to the control shaft and a second disc between the first disc and the respective diametral pin, the second disc being axially slidable along the control shaft, a compression coil spring between the second disc and the last-mentioned pin urging the second disc toward the first disc, the invention further including a switch box fixed to said housing means and having a switch actuator adapted to slide parallel with the control shaft, the switch actuator projecting between said two discs and having a limit position in the direction away from the second cylindrical sleeve so located as to cause the spring to resist pressure tending to urge the pin adjacent the first cylindrical sleeve member into its respective V-notches. 